Turbine Fuel Composition Exhibiting Improved Cold Properties

ABSTRACT

The invention relates to the use of polymers which comprise, in copolymerized form, an α-olefin, an alkenyl ester of a carboxylic acid and an ester of an α,β-unsaturated carboxylic acid as an additive for turbine fuels and in particular as a cold flow improver for turbine fuels, to the turbine fuels additized with these polymers, and to additive packets comprising such copolymers.

The invention relates to the use of polymers which comprise, incopolymerized form, an α-olefin, an ester of an α,β-unsaturatedcarboxylic acid and, if appropriate, an alkenyl ester of a carboxylicacid as an additive for turbine fuels and in particular as a cold flowimprover for turbine fuels, to the turbine fuels additized with thesepolymers, and to additive packages comprising such copolymers.

STATE OF THE ART

Turbine fuels, which are also known as aviation turbine fuels, jetfuels, aviation fuels or turbo fuels, have to satisfy high demands ontheir cold properties owing to their use in aviation and the associatedtemperature conditions. For instance, the freezing point of the turbinefuel has to be sufficiently low that the fuel flow is not impaired underthe temperature conditions prevailing at great heights and also passesthrough fuel filters without difficulty. In the case of turbine fuels,the freezing point refers to that temperature at which precipitatedhydrocarbon crystals which have formed by cooling beforehand dissolveagain fully. Depending on the field of use, the freezing point in civiland military aviation must not exceed −40° C. or about −50° C. When thetemperature goes below the freezing point, relatively long-chainparaffins crystallize out and form large, platelet-shaped wax crystals.These wax crystals have a spongelike structure and lead to inclusion ofother fuel constituents in the crystal structure. The occurrence ofthese crystals leads to the fuel being able to pass only slowly throughsmall orifices and filters. Moreover, the viscosity of the fuelincreases, as a result of which the fuel flow is worsened. Attemperatures below the pour point (PP), the fuel finally no longerflows.

At present, the freezing point of turbine fuels is adjusted inparticular by distillative measures in the refineries, for example bythe reduction of the proportion of high boiler fractions which alsocomprise wax fractions. However, a disadvantage in this context is theresulting increasing cost of the turbine fuel.

Chemical measures for freezing point depression are also known. Forinstance, EP-A-1357168 describes a turbine fuel composition which, inaddition to a turbine fuel, comprises one of the following additives:copolymers of ethylene with at least one unsaturated ester which isselected from vinyl esters having at least 5 carbon atoms,alkyl(meth)acrylates, dialkyl fumarates and dialkyl maleates;ethylene/alkene copolymers; ethylene/vinyl acetate copolymers comprisingless than 15 mol % of vinyl acetate; nucleators; waxes;alkylphenol/formaldehyde condensates; comb polymers; and organicnitrogen compounds. These additives are intended to keep turbine fuelsadditized therewith free-flowing even below the freezing point specifiedin their specification.

WO 01/62874 describes a composition which, in addition to a turbinefuel, comprises additives which are selected from the reaction productsof alkanolamines with long-chain-substituted acylating agents;phenol/aldehyde condensates; specific aromatic systems; andethylene/vinyl acetate copolymers. These additives are intended to lowerthe freezing point of the turbine fuel additized therewith.

DE 1250188 describes copolymers of ethylene and an acrylic ester with atleast 7 carbon atoms in the ester molecule, which is said to lower thepour point of heating oils, diesel fuels and jet fuels. In the examples,however, no jet fuels are used.

There is therefore still a need for additives which further improve thecold properties of turbine fuels.

BRIEF DESCRIPTION OF THE INVENTION

It was accordingly an object of the present invention to provide noveladditives of this type.

Surprisingly, this object is achieved by virtue of the unexpectedobservation that polymers which comprise, in copolymerized form, anα-olefin, an ester of an α,β-unsaturated carboxylic acid and, ifappropriate, an alkenyl carboxylate improve the cold properties, inparticular the cold flow properties, of turbine fuels and also havebetter performance than the ethylene/vinyl acetate copolymers describedin the prior art.

The invention accordingly relates firstly to the use of a polymer whichcomprises, in copolymerized form, an α-olefin, an ester of anα,β-unsaturated carboxylic acid and, if appropriate, an alkenyl ester ofa carboxylic acid as an additive for turbine fuels. In particular, thepolymers used comprise, in copolymerized form, the ester of theα,β-unsaturated carboxylic acid and the alkenyl ester present ifappropriate, in random distribution. The polymer is preferably a binarypolymer which is composed substantially of the α-olefin and the ester ofan α,β-unsaturated carboxylic acid, or is alternatively preferably aterpolymer which is composed substantially of the three aforementionedmonomers.

Preference is given to using polymers which are composed of monomerscomprising the monomers M1, M2 and, if appropriate, M3, where M1, M2 andM3 have the following general formulae

in whichR¹ is H or C₁-C₄₀-hydrocarbyl;R², R³ and R⁴ are each independently H or C₁-C₄-alkyl;R⁵ is C₁-C₂₀-hydrocarbyl;R⁶, R⁷ and R⁸ are each independently H or C₁-C₄-alkyl; andR⁹ is C₁-C₁₉-hydrocarbyl.

DETAILED DESCRIPTION OF THE INVENTION

Unless stated otherwise, the following general definitions apply in thecontext of the present invention:

C₁-C₄₀-Hydrocarbyl is a hydrocarbon radical having 1 to 40 carbon atoms.It is preferably an aliphatic hydrocarbon radical such as alkyl,alkenyl, alkadienyl or alkynyl. In particular C₁-C₄₀-hydrocarbyl isC₁-C₄₀-alkyl. C₁-C₄₀-alkyl is a linear or branched alkyl radical having1 to 40 carbon atoms. Examples of this are methyl, ethyl, n-propyl,isopropyl, n-butyl, sec-butyl, isobutyl, tert-butyl, pentyl, neopentyl,hexyl, heptyl, octyl, 2-ethylhexyl, neooctyl, nonyl, neononyl, decyl,2-propylheptyl, neodecyl, undecyl, neoundecyl, dodecyl, tridecyl,tetradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl, nonadecyl,eicosyl, hencosyl, docosyl, tricosyl, tetracosyl, pentacosyl, hexacosyl,heptacosyl, octacosyl, nonacosyl, squalyl, their constitutional isomers,higher homologs and the accompanying constitutional isomers.

The same applies to C₁-C₂₀-hydrocarbyl radicals, i.e. they are ahydrocarbon radical having from 1 to 20 carbon atoms. They arepreferably an aliphatic hydrocarbon radical such as alkyl, alkenyl,alkadienyl or alkynyl. In particular, C₁-C₂₀-hydrocarbyl isC₁-C₂₀-alkyl. C₁-C₂₀-alkyl is a linear or branched alkyl radical having1 to 20 carbon atoms. Examples of this are methyl, ethyl, n-propyl,isopropyl, n-butyl, sec-butyl, isobutyl, tert-butyl, pentyl, neopentyl,hexyl, heptyl, octyl, 2-ethylhexyl, neooctyl, nonyl, neononyl, decyl,2-propylheptyl, neodecyl, undecyl, neoundecyl, dodecyl, tridecyl,tetradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl, nonadecyl,eicosyl and their constitutional isomers.

C₁-C₁₉-Hydrocarbyl is a hydrocarbon radical having from 1 to 19 carbonatoms. It is preferably an aliphatic hydrocarbon radical such as alkyl,alkenyl, alkadienyl or alkynyl. In particular, C₁-C₁₉-hydrocarbyl isC₁-C₁₉-alkyl. C₁-C₁₉-alkyl is a linear or branched alkyl radical having1 to 19 carbon atoms. Examples of this are methyl, ethyl, n-propyl,isopropyl, n-butyl, sec-butyl, isobutyl, tert-butyl, pentyl, neopentyl,hexyl, heptyl, octyl, 2-ethylhexyl, neooctyl, nonyl, neononyl, decyl,2-propylheptyl, neodecyl, undecyl, neoundecyl, dodecyl, tridecyl,tetradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl, nonadecyl andtheir constitutional isomers.

C₁-C₁₀-Hydrocarbyl is a hydrocarbon radical having from 1 to 10 carbonatoms. It is preferably an aliphatic hydrocarbon radical such as alkyl,alkenyl, alkadienyl or alkynyl. In particular, C₁-C₁₀-hydrocarbyl isC₁-C₁₀-alkyl. C₁-C₁₀-alkyl is a linear or branched alkyl radical having1 to 10 carbon atoms. Examples of this are methyl, ethyl, n-propyl,isopropyl, n-butyl, sec-butyl, isobutyl, tert-butyl, pentyl, neopentyl,hexyl, heptyl, octyl, 2-ethylhexyl, neooctyl, nonyl, neononyl, decyl,2-propylheptyl, neodecyl and their constitutional isomers.

C₁-C₉-Hydrocarbyl is a hydrocarbon radical having from 1 to 9 carbonatoms. It is preferably an aliphatic hydrocarbon radical such as alkyl,alkenyl, alkadienyl or alkynyl. In particular, C₁-C₉-hydrocarbyl isC₁-C₉-alkyl. C₁-C₉-Alkyl is a linear or branched alkyl radical havingfrom 1 to 9 carbon atoms. Examples of this are methyl, ethyl, n-propyl,isopropyl, n-butyl, sec-butyl, isobutyl, tert-butyl, pentyl, neopentyl,hexyl, heptyl, octyl, 2-ethylhexyl, neooctyl, nonyl, neononyl and theirconstitutional isomers.

C₅-C₁₆-Hydrocarbyl is a hydrocarbon radical having from 5 to 16 carbonatoms. It is preferably an aliphatic hydrocarbon radical such as alkyl,alkenyl, alkadienyl or alkynyl. In particular, C₅-C₁₆-hydrocarbyl isC₅-C₁₆-alkyl. C₅-C₁₆-Alkyl is a linear or branched alkyl radical havingfrom 5 to 16 carbon atoms. Examples of this are pentyl, neopentyl,isopentyl, hexyl, isohexyl, heptyl, octyl, 2-ethylhexyl, neooctyl,nonyl, neononyl, isononyl, decyl, 2-propylheptyl, neodecyl, undecyl,neoundecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl andtheir constitutional isomers.

C₈-C₁₂-Hydrocarbyl is a hydrocarbon radical having from 8 to 12 carbonatoms. It is preferably an aliphatic hydrocarbon radical such as alkyl,alkenyl, alkadienyl or alkynyl. In particular, C₈-C₁₂-hydrocarbyl isC₈-C₁₂-alkyl. C₈-C₁₂-Alkyl is a linear or branched alkyl radical havingfrom 8 to 12 carbon atoms. Examples of this are octyl, 2-ethylhexyl,neooctyl, nonyl, neononyl, isononyl, decyl, 2-propylheptyl, neodecyl,undecyl, neoundecyl, dodecyl and their constitutional isomers.

C₈-C₁₄-Hydrocarbyl is a hydrocarbon radical having from 8 to 14 carbonatoms. It is preferably an aliphatic hydrocarbon radical such as alkyl,alkenyl, alkadienyl or alkynyl. In particular, C₈-C₁₄-hydrocarbyl isC₈-C₁₄-alkyl. C₈-C₁₄-Alkyl is a linear or branched alkyl radical havingfrom 8 to 14 carbon atoms. In addition to the alkyl radicals mentionedabove for C₈-C₁₂-alkyl, examples are tridecyl und tetradecyl and theirconstitutional isomers.

C₈-C₁₆-Hydrocarbyl is a hydrocarbon radical having from 8 to 16 carbonatoms. It is preferably an aliphatic hydrocarbon radical such as alkyl,alkenyl, alkadienyl or alkynyl. In particular, C₈-C₁₆-hydrocarbyl isC₈-C₁₆-alkyl. C₈-C₁₆-Alkyl is a linear or branched alkyl radical havingfrom 8 to 16 carbon atoms. In addition to the alkyl radicals mentionedabove for C₈-C₁₄-alkyl, examples are pentadecyl und hexadecyl and theirconstitutional isomers.

C₈-C₂₀-Hydrocarbyl is a hydrocarbon radical having from 8 to 20 carbonatoms. It is preferably an aliphatic hydrocarbon radical such as alkyl,alkenyl, alkadienyl or alkynyl. In particular, C₈-C₂₀-hydrocarbyl isC₈-C₂₀-alkyl. C₈-C₂₀-Alkyl is a linear or branched alkyl radical havingfrom 8 to 20 carbon atoms. In addition to the alkyl radicals mentionedabove for C₈-C₁₆-alkyl, examples are heptadecyl, octadecyl, nonadecylund eicosanyl and their constitutional isomers.

C₆-C₁₄-Hydrocarbyl is a hydrocarbon radical having from 6 to 14 carbonatoms. It is preferably an aliphatic hydrocarbon radical such as alkyl,alkenyl, alkadienyl or alkynyl. In particular, C₆-C₁₄-hydrocarbyl isC₆-C₁₄-alkyl. C₆-C₁₄-Alkyl is a linear or branched alkyl radical havingfrom 6 to 14 carbon atoms. In addition to the alkyl radicals mentionedabove for C₈-C₁₄-alkyl, examples are hexyl und heptyl and theirconstitutional isomers.

C₆-C₁₆-Hydrocarbyl is a hydrocarbon radical having from 6 to 16 carbonatoms. It is preferably an aliphatic hydrocarbon radical such as alkyl,alkenyl, alkadienyl or alkynyl. In particular, C₆-C₁₆-hydrocarbyl isC₆-C₁₆-alkyl. C₆-C₁₆-Alkyl is a linear or branched alkyl radical havingfrom 6 to 16 carbon atoms. In addition to the alkyl radicals mentionedabove for C₈-C₁₆-alkyl, examples are hexyl und heptyl and theirconstitutional isomers.

C₆-C₂₀-Hydrocarbyl is a hydrocarbon radical having from 6 to 20 carbonatoms. It is preferably an aliphatic hydrocarbon radical such as alkyl,alkenyl, alkadienyl or alkynyl. In particular, C₆-C₂₀-hydrocarbyl isC₆-C₂₀-alkyl. C₆-C₂₀-Alkyl is a linear or branched alkyl radical havingfrom 6 to 20 carbon atoms. In addition to the alkyl radicals mentionedabove for C₈-C₂₀-alkyl, examples are hexyl und heptyl and theirconstitutional isomers.

C₅-C₂₀-Hydrocarbyl is a hydrocarbon radical having from 5 to 20 carbonatoms. It is preferably an aliphatic hydrocarbon radical such as alkyl,alkenyl, alkadienyl or alkynyl. In particular, C₅-C₂₀-hydrocarbyl isC₅-C₂₀-alkyl. C₅-C₂₀-Alkyl is a linear or branched alkyl radical havingfrom 5 to 20 carbon atoms. In addition to the alkyl radicals mentionedabove for C₆-C₂₀-alkyl, examples are pentyl and its constitutionalisomers.

C₄-C₁₄-Hydrocarbyl is a hydrocarbon radical having from 4 to 14 carbonatoms. It is preferably an aliphatic hydrocarbon radical such as alkyl,alkenyl, alkadienyl or alkynyl. In particular, C₄-C₁₄-hydrocarbyl isC₄-C₁₄-alkyl. C₄-C₁₄-Alkyl is a linear or branched alkyl radical havingfrom 4 to 14 carbon atoms. In addition to the alkyl radicals mentionedabove for C₆-C₁₄-alkyl, examples are pentyl and its constitutionalisomers, and also n-butyl, sec-butyl, isobutyl und tert-butyl.

C₄-C₁₆-Hydrocarbyl is a hydrocarbon radical having from 4 to 16 carbonatoms. It is preferably an aliphatic hydrocarbon radical such as alkyl,alkenyl, alkadienyl or alkynyl. In particular, C₄-C₁₆-hydrocarbyl isC₄-C₁₆-alkyl. C₄-C₁₆-Alkyl is a linear or branched alkyl radical havingfrom 4 to 16 carbon atoms. In addition to the alkyl radicals mentionedabove for C₆-C₁₆-alkyl, examples are pentyl and its constitutionalisomers, and also n-butyl, sec-butyl, isobutyl und tert-butyl.

C₄-C₂₀-Hydrocarbyl is a hydrocarbon radical having from 4 to 20 carbonatoms. It is preferably an aliphatic hydrocarbon radical such as alkyl,alkenyl, alkadienyl or alkynyl. In particular, C₄-C₂₀-hydrocarbyl isC₄-C₂₀-alkyl. C₄-C₂₀-Alkyl is a linear or branched alkyl radical havingfrom 4 to 20 carbon atoms. In addition to the alkyl radicals mentionedabove for C₅-C₂₀-alkyl, examples are n-butyl, sec-butyl, isobutyl undtert-butyl.

C₁-C₄-Hydrocarbyl is a hydrocarbon radical having from 1 to 4 carbonatoms. It is preferably an aliphatic hydrocarbon radical such as alkyl,alkenyl, alkadienyl or alkynyl. In particular, C₁-C₄-hydrocarbyl isC₁-C₄-alkyl, such as methyl, ethyl, n-propyl, isopropyl, n-butyl,sec-butyl, isobutyl and tert-butyl.

The hydrocarbyl radicals, for example the alkyl radicals, may beunsubstituted or mono- or polysubstituted. Suitable substituents are,for example, OH, C₁-C₄-alkoxy, NR¹¹R¹² (R¹¹ and R¹² are eachindependently H or C₁-C₄-alkyl) or carbonyl (COR¹¹). However, they arepreferably unsubstituted.

C₁-C₄-Alkoxy is a C₁-C₄-alkyl radical bonded via an oxygen atom.Examples thereof are methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy,2-butoxy, isobutoxy and tert-butoxy.

C₁-C₄-Alkanol is a C₁-C₄-alkyl radical which is substituted by from 1 to3 hydroxyl groups on different carbon atoms. C₁-C₁₀-Alkanol is aC₁-C₁₀-alkyl radical which is substituted by from 1 to 6 hydroxyl groupson different carbon atoms. C₁-C₂₀-Alkanol is a C₁-C₂₀-alkyl radicalwhich is substituted by from 1 to 6 hydroxyl groups on different carbonatoms. C₁-C₄₀-Alkanol is a C₁-C₄₀-alkyl radical which is substituted byfrom 1 to 6 hydroxyl groups on different carbon atoms. Examples ofC₁-C₄-alkanols are methanol, ethanol, n-propanol, isopropanol,n-butanol, sec-butanol, isobutanol, tert-butanol, ethylene glycol,propylene glycol and glycerol.

C₁-C₁₀-Alkanol is additionally, for example, pentanol, hexanol,heptanol, octanol, 2-ethylhexanol, nonanol, decanol, theirconstitutional isomers, and also erythritol, pentaerythritol andsorbitol.

C₁-C₂₀-Alkanol is additionally, for example, undecanol, dodecanol,tridecanol, tetradecanol, pentadecanol, hexadecanol, heptadecanol,octadecanol, nonadecanol and eicosanol and their constitutional isomers.

a) Polymers Used in Accordance with the Invention

The remarks made below on the preferred embodiments of the polymers usedin accordance with the invention and of the monomers from which they areformed apply both alone and in combination.

The polymers used in accordance with the invention may comprise themonomers M1, M2 and M3 in the following molar fractions (Mx/(M1+M2+M3))in the polymer:

M1: preferably from 0.60 to 0.99;M2: preferably from 0.01 to 0.40;M3: preferably from 0 to 0.20.

In the case that the polymers used in accordance with the invention donot comprise the monomer M3 in copolymerized form:

M1: preferably from 0.60 to 0.99, more preferably from 0.7 to 0.95, inparticular from 0.75 to 0.85;M2: preferably from 0.01 to 0.6, more preferably from 0.05 to 0.3, inparticular from 0.05 to 0.25.

In the case that the polymers used in accordance with the inventioncomprise the monomer M3 in copolymerized form:

M1: preferably from 0.60 to 0.98, more preferably from 0.7 to 0.95, inparticular from 0.75 to 0.9;M2: preferably from 0.01 to 0.20, more preferably from 0.01 to 0.17, inparticular from 0.015 to 0.16;M3: preferably from 0.01 to 0.20, more preferably from 0.02 to 0.15, inparticular from 0.03 to 0.12, especially from 0.03 to 0.11.

The monomers M1 are preferably monoalkenes with a terminal double bond,such as ethylene, propylene, 1-butene, 1-pentene, 1-hexene, 1-heptene,1-octene, 1-nonene, 1-decene, their constitutional isomers and also thehigher monounsaturated homologs having up to 40 carbon atoms.

In the monomers M1, R¹ is preferably H or C₁-C₂₀-hydrocarbyl, morepreferably H or C₁-C₁₀-hydrocarbyl, and even more preferably H orC₁-C₄-hydrocarbyl. Hydrocarbyl is preferably alkyl. In particular, R¹ isH, methyl or ethyl. Accordingly, the monomer M1 is in particularethylene, propylene or 1-butene. R¹ is especially H, i.e. M1 isespecially ethylene.

In the monomer M2, the R², R³ and R⁴ radicals are preferably each H ormethyl. More preferably, two of the R², R³ and R⁴ radicals are each Hand the other radical is H or methyl. In particular, all three R², R³and R⁴ are H.

Accordingly, the monomer M2 is preferably the esters of α,β-unsaturatedcarboxylic acids which are selected from acrylic acid, methacrylic acid,crotonic acid and isocrotonic acid, more preferably from acrylic acidand methacrylic acid, and in particular acrylic acid.

Examples of such preferred α,β-unsaturated carboxylic acids M2 include:acrylic esters of C₁-C₂₀-alkanols, such as methyl acrylate, ethylacrylate, propyl acrylate, isopropyl acrylate, n-butyl acrylate,isobutyl acrylate, tert-butyl acrylate, n-pentyl acrylate, neopentylacrylate, isopentyl acrylate, hexyl acrylate, isohexyl acrylate, heptylacrylate, octyl acrylate, neooctyl acrylate, 2-ethylhexyl acrylate,nonyl acrylate, neononyl acrylate, decyl acrylate, neodecyl acrylate,2-propylheptyl acrylate, lauryl acrylate, palmityl acrylate and stearylacrylate; and also the corresponding methacrylic, crotonic andisocrotonic esters, preference being given to the acrylates (acrylicesters).

R⁵ is C₁-C₂₀-hydrocarbyl, preferably C₁-C₂₀-alkyl.

In the case that the polymer used in accordance with the inventioncomprises no alkenyl ester and especially no monomer M3, R⁵ in apreferred embodiment of the invention is a hydrocarbyl radical having atleast 5 carbon atoms, for example C₅-C₂₀-hydro-carbyl. R⁵ is morepreferably a hydrocarbyl radical having at least 6 carbon atoms, forexample C₆-C₂₀-hydrocarbyl, preferably C₆-C₁₆-hydrocarbyl or morepreferably C₆-C₁₄-hydrocarbyl. In particular, R⁵ is a hydrocarbylradical having at least 8 carbon atoms, for example C₈-C₂₀-hydrocarbyl,preferably C₈-C₁₁-hydrocarbyl and more preferably C₈-C₁₄-hydrocarbyl. R⁵is especially C₈-C₁₂-hydrocarbyl. Hydrocarbyl is preferably alkyl.Accordingly, R⁵ in this case is preferably an alkyl radical having atleast 5 carbon atoms, for example C₅-C₂₀-alkyl, R⁵ is more preferably analkyl radical having at least 6 carbon atoms, for example C₆-C₂₀-alkyl,preferably C₆-C₁₆-alkyl or more preferably C₆-C₁₄-alkyl. In particular,R⁵ is an alkyl radical having at least 8 carbon atoms, for exampleC₈-C₂₀-alkyl, preferably C₈-C₁₆-alkyl and more preferably C₈-C₁₄-alkyl.R⁵ is especially C₈-C₁₂-alkyl.

In the case that the polymer used in accordance with the inventioncomprises, in copolymerized form, an alkenyl ester and especially themonomer M3, R⁵ in a preferred embodiment of the invention isC₄-C₂₀-hydrocarbyl, for example C₄-C₁₈-hydrocarbyl or C₄-C₁₆-hydrocarbylor C₄-C₁₄-hydrocarbyl or C₄-C₁₂-hydrocarbyl, more preferablyC₅-C₂₀-hydrocarbyl, for example C₅-C₁₈-hydrocarbyl or C₅-C₁₆-hydrocarbylor C₅-C₁₄-hydrocarbyl or C₅-C₁₂-hydrocarbyl, even more preferablyC₆-C₂₀-hydrocarbyl, for example C₆-C₁₈-hydrocarbyl or C₆-C₁₆-hydrocarbylor C₆-C₁₄-hydrocarbyl or C₆-C₁₂-hydrocarbyl, and in particularC₈-C₂₀-hydrocarbyl, for example C₈-C₁₈-hydrocarbyl or C₈-C₁₆-hydrocarbylor C₈-C₁₄-hydrocarbyl or C₈-C₁₂-hydrocarbyl. R⁵ is especiallyC₈-C₁₂-hydrocarbyl. Hydrocarbyl is preferably alkyl. Accordingly, R⁵ inthis case is preferably C₄-C₂₀-alkyl, for example C₄-C₁₈-alkyl orC₄-C₁₆-alkyl or C₄-C₁₄-alkyl or C₄-C₁₂-alkyl, more preferablyC₅-C₂₀-alkyl, for example C₅-C₁₈-alkyl or C₅-C₁₆-alkyl or C₅-C₁₄-alkylor C₅-C₁₂-alkyl, even more preferably C₆-C₂₀-alkyl, for exampleC₆-C₁₈-alkyl or C₆-C₁₆-alkyl or C₆-C₁₄-alkyl or C₆-C₁₂-alkyl, and inparticular C₈-C₂₀-alkyl, for example C₈-C₁₈-alkyl or C₈-C₁₆-alkyl orC₈-C₁₄-alkyl or C₈-C₁₂-alkyl. R⁵ is especially C₈-C₁₂-alkyl.

Irrespective of their chain length and irrespective of whether thepolymer does or does not comprise an alkenyl ester, especially themonomer M3, in copolymerized form, preferred alkyl radicals R⁵ arepreferably linear or lightly branched. Lightly branched means that, inthe case of n carbon atoms in the longest carbon chain of the alkylradical, a maximum of (n−3) branches are present. Examples of suchlightly branched alkyl radicals are isopentyl (—(CH₂)₂—CH(CH₃)₂),isohexyl (—(CH₂)₃—CH(CH₃)₂), 2-ethylhexyl, isononyl(3,5,5-dimethylhexyl), 2-propylheptyl and the like. The alkyl radical R⁵is more preferably linear or comprises at most 2 branches. Inparticular, it is linear or comprises one branch.

Irrespective of whether the polymer comprises, in copolymerized form, analkenyl ester and especially the monomer M3, R⁵ is in particularn-octyl, 2-ethylhexyl, n-nonyl, isononyl, n-decyl, 2-propylheptyl,n-undecyl, lauryl (=n-dodecyl) or n-tridecyl, and especially2-ethylhexyl or lauryl.

More preferably, the monomer M2 is selected from octyl acrylate,2-ethylhexyl acrylate, n-nonyl acrylate, isononyl acrylate, n-decylacrylate, 2-propylheptyl acrylate, n-undecyl acrylate, lauryl acrylate,and n-tridecyl acrylate. In particular, the monomer M2 is selected from2-ethylhexyl acrylate and lauryl acrylate. It is especially 2-ethylhexylacrylate.

The monomer M3 is the alkenyl ester, for example a vinyl or propenylester, of an aliphatic carboxylic acid, which may be unsaturated orpreferably saturated.

Examples of the alkenyl esters, in particular of the vinyl or propenylesters, of an aliphatic carboxylic acid which may be unsaturated orpreferably saturated are the vinyl or propenyl esters of aliphaticC₂-C₂₀-carboxylic acids such as acetic acid, propionic acid, butyricacid, valeric acid, isovaleric acid, pivalic acid, neopentanoic acid,caproic acid, enanthic acid, caprylic acid, pelargonic acid,2-ethylhexanoic acid, versatic (Versatic™ acid), in particularneononanoic acid and neodecanoic acid (e.g. VeoVa™=vinyl ester ofversatic acid), capric acid, neoundecanoic acid, lauric acid,tridecanoic acid, myristic acid, pentadecanoic acid, palmitic acid,margaric acid, stearic acid, nonadecanoic acid and arachic acid.Preference is given to the vinyl esters of the carboxylic acidsmentioned.

In the monomer M3, R⁶, R⁷ and R⁸ are each independently preferably H ormethyl, and more preferably H.

R⁹ is preferably C₁-C₉-hydrocarbyl. Hydrocarbyl is preferably alkyl. R⁹is more preferably ethyl or methyl, and in particular methyl.

The monomer M3 is more preferably vinyl acetate.

In a specific embodiment of the invention, the copolymer used inaccordance with the invention comprises the monomer M3 in copolymerizedform and is thus formed from monomers comprising the monomers M1, M2 andM3.

The polymers used in accordance with the invention are preferably formedsubstantially from the above-defined monomers M1, M2 and, ifappropriate, M3. As a result of the preparation, small fractions of acompound used as a regulator (chain terminator) may be present ifappropriate.

The polymers used in accordance with the invention also have anumber-average molecular weight M_(n) in the range from about 1000 to 20000, more preferably from 1000 to 10 000, in particular from 1500 to6000 and especially from 1500 to 5000.

The polymers may also have a weight-average molecular weight M_(w) offrom 1000 to 30 000, in particular from 2000 to 20 000, and/or anM_(w)/M_(n) ratio of from 1.5 to 5.0, preferably from 1.8 to 4.0 and inparticular from 1.9 to 3.5.

The number-average and weight-average molecular weights M_(n) and M_(w)relate to values obtained by means of gel permeation chromatography(GPC).

The viscosity of such polymers (determined to Ubbelohde DIN 51562) isfrom about 5 to 25 000 mm²/s, preferably from about 10 to 1000 mm²/s, inparticular from about 50 to 700 mm²/s, in each case at a temperature ofabout 120° C.

Polymers used with preference are selected from the copolymers ofethylene and C₅-C₂₀-alkyl acrylates, e.g. C₅-C₁₈-alkyl acrylates orC₅-C₁₆-alkyl acrylates or C₅-C₁₄-alkyl acrylates, and the copolymers ofethylene, vinyl acetate and C₅-C₂₀-alkyl acrylates, e.g. C₅-C₁₈-alkylacrylates or C₅-C₁₆-alkyl acrylates or C₅-C₁₄-alkyl acrylates. Polymersused with particular preference are selected from the copolymers ofethylene and C₆-C₂₀-alkyl acrylates, e.g. C₆-C₁₈-alkyl acrylates orC₆-C₁₆-alkyl acrylates or C₆-C₁₄-alkyl acrylates, and the copolymers ofethylene, vinyl acetate and C₆-C₂₀-alkyl acrylates, e.g. C₆-C₁₈-alkylacrylates or C₆-C₁₆-alkyl acrylates or C₆-C₁₄-alkyl acrylates. Polymersused with even greater preference are selected from the copolymers ofethylene and C₈-C₂₀-alkyl acrylates, e.g. C₈-C₁₈-alkyl acrylates orC₈-C₁₆-alkyl acrylates or C₈-C₁₄-alkyl acrylates or C₈-C₁₂-alkylacrylates, and the copolymers of ethylene, vinyl acetate andC₈-C₂₀-alkyl acrylates, e.g. C₈-C₁₈-alkyl acrylates or C₈-C₁₆-alkylacrylates or C₈-C₁₄-alkyl acrylates or C₈-C₁₂-alkyl acrylates.

In particular, the polymers used are selected from ethylene/2-ethylhexylacrylate polymers, ethylene/2-ethylhexyl acrylate/vinyl acetate polymersand ethylene/lauryl acrylate/vinyl acetate polymers.

Based on a polymer composed of ethylene, 2-ethylhexyl acrylate (EHA) andvinyl acetate (VAC), the proportion by weight of the monomers is:

EHA: 4-80% by weight, preferably from 5 to 62% by weight, in particularfrom 7 to 47% by weightVAC: 1-42% by weight, preferably from 1 to 30% by weight, in particularfrom about 1 to 25% by weight, especially from 1 to 20% by weight

The difference to 100% by weight corresponds to the fraction ofethylene.

Preference is given to using the polymers as cold flow improvers.Particular preference is given to using them to lower the pour point(PP) of the turbine fuel additized therewith.

The above-described polymers are used alone or in combination with othersuch polymers in amounts which are sufficient to exhibit an effect onthe cold properties, in particular on the cold flow performance of theturbine fuel additized therewith.

The polymers used in accordance with the invention may also be used incombination with further conventional cold flow improvers and/or furtherturbine fuel additives.

b) Preparation of the Polymers

The polymers used in accordance with the invention are prepared byprocesses known per se. Preference is given to preparing them byfree-radical polymerization, in particular high-pressure polymerization,of the monomers M1, M2 and, if appropriate, M3. Such processes fordirect free-radical high-pressure copolymerization of unsaturatedcompounds are known from the prior art (cf., for example, Ullmann'sEncyclopedia of Industrial Chemistry 5th edition, “Waxes”, Vol. A 28, p.146 ff., VCH Weinheim, Basle, Cambridge, New York, Tokyo, 1996; and alsoU.S. Pat. No. 3,627,838; DE-A 2515805; DE-A 3141507; EP-A 0007590).

The copolymers which are to be used in accordance with the invention andare obtainable by the polymerization process are preferably formedsubstantially from the above-defined monomers M1, M2 and, ifappropriate, M3. As a result of the preparation, small proportions of acompound used as a regulator (chain terminator) may be present ifappropriate.

The copolymers are preferably prepared in stirred high-pressureautoclaves or in high-pressure stirred reactors or combinations of thetwo. In this apparatus, the length/diameter ratio varies predominantlywithin ranges of from 5:1 to 30:1, preferably 10:1 to 20:1.

Suitable pressure conditions for the polymerization are from 1000 to3000 bar, preferably from 1500 to 2000 bar. The reaction temperaturesare, for example, in the range from 160 to 320° C., preferably in therange from 200 to 280° C.

The regulator used to control the molecular weight of the copolymers is,for example, an aliphatic aldehyde or an aliphatic ketone of the generalformula I

or mixtures thereof.

In the formula, the R^(a) and R^(b) radicals are the same or differentand are selected from

-   -   hydrogen;    -   C₁-C₆-alkyl such as methyl, ethyl, n-propyl, isopropyl, n-butyl,        isobutyl, sec-butyl, tert-butyl, n-pentyl, isopentyl,        sec-pentyl, neopentyl, 1,2-dimethylpropyl, isoamyl, n-hexyl,        isohexyl, sec-hexyl; more preferably C₁-C₄-alkyl such as methyl,        ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl and        tert-butyl;    -   C₃-C₁₂-cycloalkyl such as cyclopropyl, cyclobutyl, cyclopentyl,        cyclohexyl, cycloheptyl, cyclooctyl, cyclononyl, cyclodecyl,        cycloundecyl and cyclododecyl; preference is given to        cyclopentyl, cyclohexyl and cycloheptyl.

The R^(a) and R^(b) radicals may also be covalently bonded to oneanother to form a 4- to 13-membered ring. For example, R^(a) and R^(b)together may form the following alkylene groups: —(CH₂)₄—, —(CH₂)₅—,—(CH₂)₆—, —(CH₂)₇—, —CH(CH₃)—CH₂—CH₂—CH(CH₃)— or—CH(CH₃)—CH₂—CH₂—CH₂—CH(CH₃)—.

Very particular preference is given to the use of propionaldehyde orethyl methyl ketone as a regulator.

Further very suitable regulators are unbranched aliphatic hydrocarbons,for example propane, or branched aliphatic hydrocarbons having tertiaryhydrogen atoms, for example isobutane, isopentane, isooctane orisododecane (2,2,4,6,6-pentamethylheptane). Further additionalregulators which can be used are higher olefins, for example propylene.

Preference is likewise given to mixtures of the above regulators withhydrogen or hydrogen alone.

The amount of regulator used corresponds to the amounts customary forthe high-pressure polymerization process.

Useful initiators for the free-radical polymerization are the customaryfree-radical initiators, for example organic peroxides, oxygen or azocompounds. Also suitable are mixtures of a plurality of free-radicalinitiators. Useful free-radical initiators include, for example, one ormore peroxides selected from the following commercially obtainablesubstances:

-   -   didecanoyl peroxide,        2,5-dimethyl-2,5-di(2-ethylhexanoylperoxy)hexane, tert-amyl        peroxy-2-ethylhexanoate, dibenzoyl peroxide, tert-butyl        peroxy-2-ethylhexanoate, tert-butyl peroxydiethyl acetate,        tert-butyl peroxydiethyl isobutyrate,        1,4-di(tert-butylperoxycarbo)cyclohexane as an isomer mixture,        tert-butyl perisononanoate,        1,1-di(tert-butylperoxy)-3,3,5-trimethylcyclohexane,        1,1-di(tert-butylperoxy)cyclohexane, methyl isobutyl ketone        peroxide, tert-butyl peroxyisopropyl carbonate,        2,2-di-tert-butylperoxy)butane or tert-butyl peroxyacetate;    -   tert-butyl peroxybenzoate, di-tert-amyl peroxide, dicumyl        peroxide, the isomeric di(tert-butylperoxyisopropyl)benzenes,        2,5-dimethyl-2,5-di-tert-butylperoxyhexane, tert-butyl cumyl        peroxide, 2,5-dimethyl-2,5-di(tert-butylperoxy)hex-3-yne,        di-tert-butyl peroxide, 1,3-diisopropyl monohydroperoxide,        cumene hydroperoxide or tert-butyl hydroperoxide; or    -   dimeric or trimeric ketone peroxides, as disclosed, for example,        by EP-A 0 813 550.

Particularly suitable peroxides are di-tert-butyl peroxide, tert-butylperoxypivalate, tert-butyl peroxyisononanoate or dibenzoyl peroxide ormixtures thereof. An example of an azo compound isazobisisobutyronitrile (AIBN). The free-radical initiators are used inamounts customary for polymerizations.

In a preferred method, the polymers to be used in accordance with theinvention are prepared in such a way that a mixture of the monomers M1,M2 and, if appropriate, M3 is passed in the presence of the regulator ata temperature within the range from about 20 to 50° C., for example of30° C., preferably continuously, through a stirred autoclave which ismaintained at a pressure in the range from about 1500 to 2000 bar, forexample of about 1700 bar. The preferably continuous addition ofinitiator which is generally dissolved in a suitable solvent, forexample isododecane, keeps the temperature in the reactor at the desiredreaction temperature, for example at from 200 to 250° C. The polymerobtained after decompression of the reaction mixture is then isolated ina customary manner.

Modifications to this method are of course possible and can beundertaken by those skilled in the art without unreasonable effort. Forexample, the comonomers and the regulator can be separately metered intothe reaction mixture, or the reaction temperature can be varied duringthe process, to name only a few examples.

c) Turbine Fuel Compositions

The invention further relates to turbine fuel compositions comprising amajor proportion by weight of a turbine fuel and a minor proportion byweight of at least one polymer used in accordance with the invention, asdefined above.

In the context of the present invention, the polymers used in accordancewith the invention may be used in combination with further conventionalcold flow improvers and/or further turbine fuel additives.

The turbine fuel composition comprises a majority of a liquid turbinefuel, which may be a turbine fuel customary in civil or militaryaviation. These include, for example, fuels of the designations Jet A,Jet A-1, Jet B, JP-4, JP-5, JP-7, JP-8 and JP-8+100. Jet A and Jet A-1are commercially obtainable turbine fuel specifications based onkerosine. The accompanying standards are ASTM D 1655 and DEF STAN 91-91.According to their particular specification, Jet A and Jet A-1 havemaximum freezing points of, respectively, −40° C. and −47° C. Jet B is afuel which has been further fractionated and is based on naphtha andkerosine fractions. JP-4 is equivalent to Jet B. JP 4, JP-5, JP-7, JP-8and JP-8+100 are military turbine fuels, as used, for example, by themarines and air force. Some of these standards designate formulationswhich already comprise further additives such as corrosion inhibitors,icing inhibitors, static dissipaters, etc. Preferred turbine fuels areJet A, Jet A-1 and JP 8.

The polymer used in accordance with the invention is preferably used ina proportion, based on the total amount of the turbine fuel composition,which in itself has a substantially sufficient influence on the coldflow properties of the turbine fuel composition. Preference is given tousing the polymer in an amount of from 10 to 10 000 mg/l, morepreferably from 50 to 7000 mg/l, in particular from 100 to 5000 mg/l,based on 1 l of the turbine fuel composition.

d) Coadditives

The polymers used in accordance with the invention may be added to theturbine fuel compositions individually or as a mixture of such polymersand, if appropriate, in combination with further additives known per se.

Suitable additives which may be present in the inventive turbine fuelcompositions comprise further additives which improve the coldproperties of the fuel (cold flow improvers), detergents, corrosioninhibitors, antioxidants such as sterically hindered tert-butylphenolsor N-butylphenylenediamines, metal deactivators such asN,N′-disalicylidene-1,2-diaminopropane, solubilizers, antistats such asStadis 450, biocides, antiicing agents such as diethylene glycol methylether, and mixtures thereof.

Conventional cold flow improvers include in particular:

-   (a) copolymers of ethylene with at least one further ethylenically    unsaturated monomer which are different from the polymers used in    accordance with the invention;-   (b) comb polymers;-   (c) nucleators;-   (d) polar nitrogen compounds;-   (e) sulfo carboxylic acids or sulfonic acids or their derivatives;-   (f) poly(meth)acrylic esters;-   (g) reaction products of alkanolamines with acylating agents;-   (h) condensation products of hydroxyaromatics with aldehydes; and-   (i) waxes.

In the copolymers of ethylene with at least one further ethylenicallyunsaturated monomer (a), the monomer is preferably selected fromalkenylcarboxylic esters, (meth)acrylic esters, fumaric esters, maleicesters and olefins.

Suitable olefins are, for example, those having from 3 to 20 carbonatoms and having from 1 to 3, preferably having 1 or 2, carbon-carbondouble bonds, in particular having one carbon-carbon double bond. In thelatter case, the carbon-carbon double bond may either be terminalα-olefins) or internal. However, preference is given to α-olefins,particular preference to α-olefins having from 3 to 20, more preferablyfrom 3 to 10 and in particular from 3 to 6 carbon atoms, such aspropene, 1-butene, 1-pentene and 1-hexene.

Suitable (meth)acrylic esters are, for example, esters of (meth)acrylicacid with C₁-C₁₀-alkanols, in particular with methanol, ethanol,propanol, isopropanol, n-butanol, sec-butanol, isobutanol, tert-butanol,pentanol, hexanol, heptanol, octanol, 2-ethylhexanol, nonanol anddecanol. The notation “(meth)acrylic acid” is intended to express thatboth acrylic acid and methacrylic acid are comprised.

Suitable alkenylcarboxylic esters are, for example, the vinyl andpropenyl esters of carboxylic acids having from 2 to 20 carbon atoms,whose hydrocarbon radical may be linear or branched. Among these,preference is given to the vinyl esters. Among the carboxylic acidshaving branched hydrocarbon radicals, preference is given to those whosebranch is disposed in the α-position to the carboxyl group, andparticular preference is given to the α-carbon atom being tertiary, i.e.to the carboxylic acid being a neocarboxylic acid.

Examples of suitable alkenylcarboxylic esters are vinyl acetate, vinylpropionate, vinyl butyrate, vinyl neopentanoate, vinyl hexanoate, vinyloctanoate, vinyl 2-ethylhexanoate, vinyl neononanoate, vinylneodecanoate and the corresponding propenyl esters, preference beinggiven to the vinyl esters. A particularly preferred alkenylcarboxylicester is vinyl acetate.

Particular preference is given to selecting the ethylenicallyunsaturated monomer from alkenylcarboxylic esters.

Also suitable are copolymers which comprise, in copolymerized form, twoor more different alkenylcarboxylic esters which differ in the alkenylfunction and/or in the carboxylic acid group. Likewise suitable arecopolymers which, in addition to the alkenylcarboxylic ester(s),comprise at least one copolymerized olefin and/or at least onecopolymerized (meth)acrylic ester.

The ethylenically unsaturated monomer is copolymerized in the copolymerin an amount of preferably from 1 to 50 mol %, more preferably from 10to 50 mol % and in particular from 5 to 20 mol %, based on the overallcopolymer. The copolymer (a) preferably has a number-average molecularweight M_(n) of from 1000 to 20 000, more preferably from 1000 to 10 000and in particular from 1000 to 6000.

Such ethylene copolymers (a) are described, for example, in WO 01/62874or EP-A 1357168, which are hereby fully incorporated by reference.

Comb polymers (b) are, for example, those described in “Comb-LikePolymers, Structure and Properties”, N. A. Platé and V. P. Shibaev, J.Poly. Sci. Macromolecular Revs. 8, pages 117 to 253 (1974). Among thosedescribed there, suitable comb polymers are, for example, those of theformula II

in which

D is R¹⁷, COOR¹⁷, OCOR⁷, R¹⁸, OCOR¹⁸ or OR¹⁷, E is H, CH₃, D or R¹⁸, Gis H or D,

J is H, R¹⁸, R¹⁸COOR¹⁷, aryl or heterocyclyl,

K is H, COOR¹⁸, OCOR¹⁸, OR¹⁸ or COOH,

L is H, R¹⁸, COOR¹⁸, OCOR¹⁸, COOH or aryl,whereR¹⁷ is a hydrocarbon radical having at least 10 carbon atoms, preferablyhaving from 10 to 30 carbon atoms,R¹⁸ is a hydrocarbon radical having at least one carbon atom, preferablyhaving from 1 to 30 carbon atoms,m is a molar fraction in the range from 1.0 to 0.4 andn is a molar fraction in the range from 0 to 0.6.

Preferred comb polymers are obtainable, for example, by copolymerizationof maleic anhydride or fumaric acid with another ethylenicallyunsaturated monomer, for example with an α-olefin or an unsaturatedester, such as vinyl acetate, and subsequent esterification of theanhydride or acid function with an alcohol having at least 10 carbonatoms. Further preferred comb polymers are copolymers of α-olefins andesterified comonomers, for example esterified copolymers of styrene andmaleic anhydride or esterified copolymers of styrene and fumaric acid.Also suitable are mixtures of comb polymers. Comb polymers may also bepolyfumarates or polymaleates. Homo- and copolymers of vinyl ethers arealso suitable comb polymers.

Suitable nucleators (c) are in particular polyoxyalkylenes, for examplepolyoxyalkylene esters, ethers, ester/ethers and mixtures thereof. Thepolyoxyalkylene compounds preferably comprise at least one, morepreferably at least two, linear alkyl group(s) having from 10 to 30carbon atoms and a polyoxyalkylene group having a molecular weight of upto 5000. The alkyl group of the polyoxyalkylene radical preferablycomprises from 1 to 4 carbon atoms. Such polyoxyalkylene compounds aredescribed, for example, in EP-A-0 061 895, in EP-A 1357168 and in U.S.Pat. No. 4,491,455, which are hereby fully incorporated by reference.Preferred polyoxyalkylene esters, ethers and ester/ethers have thegeneral formula III

R¹⁹O—(CH₂)_(y)_(x)O—R²⁰  (III)

in whichR¹⁹ and R²⁰ are each independently R²¹, R²¹—CO—, R²¹—O—CO(CH₂)_(z)— orR²¹—O—CO(CH₂)_(z)—CO—, where R²¹ is linear C₁-C₃₀-alkyl,y is from 1 to 4,x is from 2 to 200, andz is from 1 to 4.

Preferred polyoxyalkylene compounds of the formula III in which both R¹⁹and R²⁰ are R²¹ are polyethylene glycols and polypropylene glycolshaving a number-average molecular weight of from 100 to 5000. Preferredpolyoxyalkylenes of the formula III in which one of the R¹⁹ radicals isR²¹ and the other is R²¹—CO— are polyoxyalkylene esters of fatty acidshaving from 10 to 30 carbon atoms, such as stearic acid or behenic acid.Preferred polyoxyalkylene compounds in which both R¹⁹ and R²⁰ are anR²¹—CO— radical are diesters of fatty acids having from 10 to 30 carbonatoms, preferably of stearic acid or behenic acid.

Further suitable nucleators (c) are block copolymers as described inEP-A-1357168, whose contents are hereby fully incorporated by reference.Suitable block copolymers comprise at least one crystallizable block andat least one noncrystallizable block. The copolymers may be diblock,triblock or higher block copolymers. Preferred triblock copolymers havea crystallizable block at both polymer ends.

Such block copolymers are preferably formed from butadiene and isopreneunits.

The polar nitrogen compounds (d) are also referred to as waxantisettling additives (WASA). They are advantageously oil-soluble, maybe either ionic or nonionic and preferably have at least one, morepreferably at least 2, substituent(s) of the formula >NR²² in which R²²is a C₈-C₄₀-hydrocarbon radical. The nitrogen substituents may also bequaternized, i.e. be in cationic form. One example of such nitrogencompounds is that of ammonium salts and/or amides which are obtainableby the reaction of at least one amine substituted with at least onehydrocarbon radical with a carboxylic acid having from 1 to 4 carboxylgroups or with a suitable derivative thereof. The amines preferablycomprise at least one linear C₈-C₄₀-alkyl radical. Suitable primaryamines are, for example, octylamine, nonylamine, decylamine,undecylamine, dodecylamine, tetradecylamine and the higher linearhomologs. Suitable secondary amines are, for example, dioctadecylamineand methylbehenylamine. Also suitable are amine mixtures, in particularamine mixtures obtainable on the industrial scale, such as fatty aminesor hydrogenated tallamines, as described, for example, in Ullmann'sEncyclopedia of Industrial Chemistry, 6th Edition, 2000 electronicrelease, “Amines, aliphatic” chapter. Acids suitable for the reactionare, for example, cyclohexane-1,2-dicarboxylic acid,cyclohexene-1,2-dicarboxylic acid, cyclopentane-1,2-dicarboxylic acid,naphthalenedicarboxylic acid, phthalic acid, isophthalic acid,terephthalic acid and succinic acids substituted with long-chainhydrocarbon radicals.

A further example of polar nitrogen compounds is that of ring systemswhich bear at least two substituents of the formula -A-NR²³R²⁴ in whichA is a linear or branched aliphatic hydrocarbon group which isoptionally interrupted by one or more groups selected from O, S, NR³⁵and CO, and R²³ and R²⁴ are each a C₉-C₄₀-hydrocarbon radical which isoptionally interrupted by one or more groups selected from O, S, NR³⁵and CO, and/or substituted by one or more substituents selected from OH,SH and NR³⁵R³⁶ where R³⁵ is C₁-C₄₀-alkyl which is optionally substitutedby one or more moieties selected from CO, NR³⁵, O and S, and/orsubstituted by one or more radicals selected from NR³⁷R³⁸, OR³⁷, SR³⁷,COR³⁷, COOR³⁷, CONR³⁷R³⁸, aryl or heterocyclyl, where R³⁷ and R³⁸ areeach independently selected from H or C₁-C₄-alkyl; and R³⁶ is H or R³⁵.

A is preferably a methylene or polymethylene group having from 2 to 20methylene units. Examples of suitable R²³ and R²⁴ radicals are2-hydroxyethyl, 3-hydroxypropyl, 4-hydroxybutyl, 2-ketopropyl,ethoxyethyl and propoxypropyl. The cyclic system may be homocyclic,heterocyclic, fused polycyclic or nonfused polycyclic systems. The ringsystem is preferably carbo- or heteroaromatic, in particularcarboaromatic. Examples of such polycyclic ring systems are fusedbenzoid structures such as naphthalene, anthracene, phenanthrene andpyrene, fused nonbenzoid structures such as azulene, indene, hydrindeneand fluorene, nonfused polycycles such as diphenyl, heterocycles such asquinoline, indole, dihydroindole, benzofuran, coumarin, isocoumarin,benzothiophene, carbazole, diphenylene oxide and diphenylene sulfide,nonaromatic or partly saturated ring systems such as decalin, andthree-dimensional structures such as α-pinene, camphene, bornylene,norbornane, norbornene, bicyclooctane and bicyclooctene.

A further example of suitable polar nitrogen compounds is that ofcondensates of long-chain primary or secondary amines with carboxylgroup-comprising polymers.

The polar nitrogen compounds mentioned here are described in WO 00/44857and also in the references cited therein, which are hereby fullyincorporated by reference.

Suitable polar nitrogen compounds are also described, for example, inDE-A-198 48 621 and DE-A-196 22 052, EP-A-1357168 or EP-B 398 101, whichare hereby incorporated by reference.

Suitable sulfo carboxylic acids/sulfonic acids or their derivatives (e)are, for example, those of the general formula IV

in whichY is SO₃ ⁻(NR²⁵ ₃R²⁶)⁺, SO₃ ⁻(NHR²⁵ ₂R²⁶)⁺, SO₃ ⁻(NH₂R²⁵R²⁶), SO₃⁻(NH₃R²⁶) or SO₂NR²⁵R²⁶,X is Y, CONR²⁵R²⁷, CO₂ ⁻(NR²⁵ ₃R²⁷)⁺, CO₂ ⁻(NHR²⁵ ₂R²⁷)+R²⁸—COOR²⁷,NR²⁵COR²⁷, R²⁸OR²⁷, R²⁸OCOR²⁷, R²⁸R²⁷, N(COR²⁵)R²⁷ or Z⁻(NR²⁵ ₃R²⁷)

where

R²⁵ is a hydrocarbon radical,R²⁶ and R²⁷ are each alkyl, alkoxyalkyl or polyalkoxyalkyl having atleast 10 carbon atoms in the main chain,R²⁸ is C₂-C₅-alkylene,Z⁻ is one anion equivalent andA and B are each alkyl, alkenyl or two substituted hydrocarbon radicalsor, together with the carbon atoms to which they are bonded, form anaromatic or cycloaliphatic ring system.

Such sulfo carboxylic acids and sulfonic acids and their derivatives aredescribed in EP-A-0 261 957, which is hereby fully incorporated byreference.

Suitable poly(meth)acrylic esters (f) are either homo- or copolymers ofacrylic and methacrylic esters. Preference is given to acrylic esterhomopolymers which derive from C₁-C₄₀-alcohols. Preference is given tocopolymers of at least two different (meth)acrylic esters which differin the esterified alcohol. If appropriate, the copolymer comprises afurther, different copolymerized olefinically unsaturated monomer. Theweight-average molecular weight of the polymer is preferably from 50 000to 500 000. A particularly preferred polymer is a copolymer ofmethacrylic acid and methacrylic esters of saturated C₁₄- andC₁₅-alcohols, in which the acid groups have been neutralized withhydrogenated tallamine. Suitable poly(meth)acrylic esters are described,for example, in WO 00/44857, which is fully incorporated herein by wayof reference.

To prepare suitable reaction products of alkanolamines with acrylinatingagents (g), the acylinating agents used are preferably those whichcomprise a hydrocarbon radical having from 8 to 50 carbon atoms.Examples thereof are succinic acids or succinic acid derivativessubstituted by C₈-C₅₀-alkyl or alkenyl radical, preferably C₁₂-C₃₅-alkylor alkenyl radical. The alkanolamines are, for example, diethanolamine,dipropanolamine, dibutanolamine, N-methylethanolamine orN-ethylethanolamine. Such compounds are described, for example, in WO01/62874, which is hereby incorporated by reference.

The hydroxyaromatics used to prepare the condensation products ofhydroxyaromatics with aldehydes (h) are those which are substituted by alinear or branched hydrocarbon radical. The hydroxyaromatic may eitherbe a substituted phenol or any other hydroxy-containing aromatic such asnaphthol. The aldehyde component used may either be the aldehydesthemselves or suitable aldehyde sources. Examples of suitable aldehydesare formaldehyde (which may be used, for example, as paraldehyde ortrioxane), acetaldehyde, propanol, butanal, isobutyraldehyde, heptanal,2-ethylhexanal and glyoxalic acid. Suitable condensation products aredescribed, for example, in WO 01/62874 or in EP-A-1357168, which arehereby incorporated by reference.

Suitable waxes (I) are both linear and nonlinear paraffins. Then-paraffins are preferably C₈-C₃₅-alkanes, more preferablyC₈-C₃₀-alkanes and in particular C₈-C₂₅-alkanes. The nonlinear paraffinscomprise preferably amorphous solids having a melting point of from 10to 60° C. and a molecular weight of from 150 to 500. Such waxes aredescribed, for example, in EP-A-1357168, which is hereby incorporated byreference.

e) Additive Packages

The invention lastly also relates to additive packages comprising atleast one polymer used in accordance with the invention, as definedabove, and at least one further conventional turbine fuel additive, andalso, if appropriate, at least one diluent.

Suitable conventional turbine fuel additives are the above-describedcoadditives. Preferred coadditives are antiicing additives; and also theconventional cold flow improvers mentioned, preference being given tothose of group (a); corrosion inhibitors; detergents; antioxidants;antistats and metal deactivators. In particular, the additive packagecomprises, in addition to at least one of the above-described polymers,at least one antiicing agent and, if appropriate, at least one of thefollowing coadditives: conventional cold flow improvers, preferencebeing given to those of group (a); corrosion inhibitors; detergents;antioxidants; antistats and metal deactivators.

In the additive packages, the polymer used in accordance with theinvention is present in an amount of preferably from 0.1 to 99% byweight, more preferably from 1 to 95% by weight and in particular from 5to 90% by weight.

The additive package may also, if appropriate, comprise at least onediluent. Suitable diluents are, for example, fractions obtained duringoil processing, such as kerosine, naphtha or brightstock. Additionallysuitable are aromatic hydrocarbons such as Solvent Naphtha heavy,Solvesso® or Shellsol®, and aliphatic hydrocarbons.

When the package comprises a diluent, the polymer used in accordancewith the invention is present in the concentrates preferably in anamount of from 0.1 to 90% by weight, more preferably from 1 to 80% byweight and in particular from 10 to 70% by weight, based on the totalweight of the concentrate.

The inventive use of the polymers described improves the cold flowproperties of the turbine fuels additized therewith. In particular, thefreezing point, the cloud point (CP) and in particular the pour point(PP) are lowered.

The invention will now be illustrated in detail with reference to thenonlimiting examples which follow.

EXPERIMENTAL SECTION 1. Preparative Examples 1 to 28

A total of 28 different polymers to be used in accordance with theinvention were prepared by high-pressure polymerization of ethylene and2-ethylhexyl acrylate (EHA) or of ethylene, 2-ethylhexyl acrylate (EHA)or lauryl acrylate (LA) and vinyl acetate (VAC).

Table 1 compares the properties of the polymers used in the testexamples which follow.

The content of ethylene, EHA or LA and VAC in the resulting polymers wasdetermined by NMR spectroscopy. The viscosities were determined at 120°C. to Ubbelohde DIN 51562.

TABLE 1 Polymer E VAC Acrylate Viscosity No. [mol %] [mol %] [mol %][mm²/s] M_(n) M_(w) M_(w)/M_(n) 1 79.9 — 20.1¹ 150 3197 8499 2.66 2 88.04.2 7.8¹ 60 2088 4189 2.01 3 88.0 4.4 7.6¹ 150 2959 6666 2.25 4 88.1 4.47.5¹ 605 4635 12 811   2.76 5 86.6 3.9 9.5¹ 60 2124 4285 2.02 6 86.4 4.39.3¹ 150 3022 6754 2.23 7 86.4 4.1 9.5¹ 595 4797 13 238   2.76 8 83.84.1 12.1¹ 60 2064 4280 2.07 9 83.2 4.4 12.4¹ 150 2994 7203 2.41 10 83.14.4 12.5¹ 600 4744 14 503   3.06 11 80.2 4.5 15.3¹ 150 3038 7279 2.40 1280.4 4.1 15.5¹ 600 4681 15 697   3.35 13 89.6 8.0 2.4¹ 60 1977 3910 1.9814 89.8 7.9 2.3¹ 150 2831 6212 2.19 15 89.2 8.2 2.6¹ 605 3862 11 098  2.87 16 89.8 8.4 4.8¹ 60 1928 3902 2.02 17 86.5 8.4 5.1¹ 150 2926 63372.17 18 86.3 8.5 5.2¹ 620 4613 12 019   2.61 19 84.2 8.1 7.7¹ 60 20034025 2.01 20 83.1 8.7 8.2¹ 150 2855 6382 2.24 21 84.3 8.0 7.7¹ 615 485813 061   2.69 22 81.1 7.9 11.0¹ 60 2100 4276 2.04 23 80.8 8.0 11.2¹ 1502878 6634 2.31 24 81.1 7.6 11.3¹ 630 4774 14 263   2.99 25 77.6 8.713.7¹ 150 3134 7195 2.30 26 86.8 4.8 8.4¹ 60 1928 3902 2.02 27 86.3 5.28.5¹ 620 4613 12019  2.61 28 87.9 10.5 1.6² 153 3100 7301 2.36 E:ethylene VAC: vinyl acetate ¹2-ethylhexyl acrylate ²lauryl acrylate

2. Test Examples

The polymers 1 to 28 prepared above were used to carry out theexperiments which follow. For comparative purposes, a conventionalethylene/vinyl acetate copolymer was also tested:

A Jet A turbine fuel having a pour point (PP) of −48° C. was additizedfirstly with a conventional ethylene/vinyl acetate copolymer andsecondly with the copolymers from examples 1, 17 and 25 to 28 in anamount of in each case 1000 mg/l, and the PP value of the additizedturbine fuel was determined in each case to ISO 3016. The PP value ofthe turbine fuel additized with the conventional ethylene/vinyl acetatecopolymer was −48° C., i.e. it had not been possible to reduce it. ThePP values of the turbine fuel additized in each case with the copolymersused in accordance with the invention are listed in the table whichfollows.

TABLE 2 Polymer No. PP [° C.] — −48 EVA* −48  1 <−68 17 −63 25 <−70 26−63 27 −51 28 −51 *EVA = conventional ethylene/vinyl acetate copolymer(comparative example)

As the examples show, the Jet A turbine fuel additized with thecopolymers used in accordance with the invention has a distinctly lowerpour point than the unadditized fuel, while the conventionalethylene/vinyl acetate copolymer has no effect on the pour point.

1-16. (canceled) 17: An additive for turbine fuels comprising a polymerwhich is composed of monomers comprising M1, M2 and, optionally, M3where M1, M2 and M3 have the following general formulae:

in which R¹ is H or C₁-C₄₀-hydrocarbyl; R², R³ and R⁴ are eachindependently H or C₁-C₄-alkyl; R⁵ is unsubstituted C₁-C₂₀-alkyl or, inthe case that the polymer does not comprise monomer M3 in copolymerizedform, is unsubstituted C₆-C₂₀-alkyl; R⁶, R⁷ and R⁸ are eachindependently H or C₁-C₄-alkyl; and R⁹ is methyl or ethyl. 18: Theadditive according to claim 17, wherein the polymer comprises, incopolymerized form, the monomers M1, M2 and, optionally, M3 in randomdistribution. 19: The additive according to claim 17, wherein themonomers M1, M2 and M3 are present in the following molar fractions inthe polymer: M1: from 0.60 to 0.99 M2: from 0.01 to 0.40 M3: 0 to 0.20.20: The additive according to claim 17, wherein monomer M1 is ethylene.21: The additive according to claim 17, wherein R², R³ and R⁴ are each Hor two of the R², R³ and R⁴ radicals are each H and the other radical ismethyl. 22: The additive according to claim 17, wherein R⁵ isC₈-C₂-alkyl. 23: The additive according to claim 22, wherein R⁵ is2-ethylhexyl or lauryl. 24: The additive according to claim 17, whereinM2 is 2-ethylhexyl acrylate or lauryl acrylate. 25: The additiveaccording to claim 17, wherein M3 is vinyl acetate. 26: The additiveaccording to claim 17, wherein the polymer is used as a cold flowimprover. 27: The additive according to claim 26, wherein the polymerdecreases the pour point of the turbine fuel mixed therewith. 28: Aturbine fuel composition comprising a major proportion by weight of aturbine fuel and a minor proportion by weight of at least one additiveas defined in claim
 17. 29: The composition according to claim 17,wherein the polymer is used in combination with additional turbine fueladditives. 30: An additive package comprising at least one polymer asdefined in claim 17 in combination with at least one additional turbinefuel additive and, optionally, at least one diluent.